Various types of drive devices for hybrid vehicles having engines and motors have been proposed. For example, there is known a drive device including an input shaft coupled with an engine to be rotatable, an output shaft integrally coupled with a rotor of a motor, and a clutch device coupling the input shaft and the output shaft so that the input shaft and the output shaft are capable of being engaged by or released from each other. The output shaft is coupled with a transmission directly or through a torque converter, so that a power train leading to drive wheels is configured. According to this configuration, a vehicle can use only one of the engine and the motor to run, or use both of the engine and the motor when requiring a large driving force. Further, the motor of vehicle can be used as an electric generator so that a battery is charged by energy regeneration when the engine is driven or when braking the vehicle.
In the above-mentioned configuration, since the input shaft and the output shaft are engaged by or released from each other, the input shaft and the output shaft can rotate independently from each other. Therefore, in order to detect a rotation angle or rotation speed of the rotor of the motor and the output shaft, a rotation angle sensor is generally used. A resolver is frequently used as the rotation angle sensor. A resolver rotor is provided on a rotating member side, and a resolver stator is provided on a static case side. In mounting the resolver rotor and the resolver stator, it is important to eliminate a backlash, which causes a reduction of detection accuracy, specifically, a backlash in a rotation direction. Additionally, since the resolver rotor receives an external force according to acceleration and deceleration with rotating, the resolver rotor is required to have a stable mounting structure. Examples of technologies regarding this kind of resolver mounting structure are disclosed in JP-A-2004-222488 and JP-A-2006-158005.
A brushless motor of JP-A-2004-222488 has a rotation sensor and has a rotor unit for a resolver in an exemplary embodiment. Further, an engagement protrusion of an intercalated member on a rotor shaft side is engaged with an engagement groove formed on the rotor unit for the resolver, so that the rotor unit for the resolver is mounted. Furthermore, the rotor unit for the resolver is interposed between the above-mentioned intercalated member and a stopper having an approximately cylindrical shape, so that dropping in an axis direction is suppressed. Meanwhile, a fixing structure of a resolver rotor of JP-A-2006-158005, a resin is injected and solidified between a hole of the resolver rotor and a rotation shaft disposed inside the hole, so as to fix the resolver rotor. Further, a protrude-shape rotor key is provided at the hole of the resolver rotor to protrude toward the inner circumferential side, and the rotor key is fitted into a convex-shape groove of the rotation shaft.